Hopefully some affordable 6L6GC, and then I'll also need a rectifier tube and another one.

Sovtek 5AR4 for rectifier and Electro-Harmonix KT88 or 5881WXT (6L6 variant) for power tube. They both are at Partsconnexion; prices aren't too bad. I prefer the sound of 5881 old stock but they are more $ than a EH-KT88 which I like VERY much. I think George uses them and recommends them as well. I've had a pair of the EH-kt88s running in various amps for years now still test new.

For tubes which tube are you thinking about using?? For driver I'd get an old stock 12AT7 - I don't like the sound of the reproduction (12AT7) tubes at all. The old stock sound very good and readily available look for Sylvania they should be in expensive and sound good. You can upgrade them later if you want to roll tubes in. Trust me on the new stock driver tubes they will make the amp sound like crap.

Cheers,
Bob

A +1 on the Sylvania.. I'm using a NOS Sylvania 12AT7 w/black plates and it sounds great.... even better than the Amperex Bugle Boy it replaced. The price wasn't too bad either...

Sovtek 5AR4 for rectifier and Electro-Harmonix KT88 or 5881WXT (6L6 variant) for power tube. They both are at Partsconnexion; prices aren't too bad. I prefer the sound of 5881 old stock but they are more $ than a EH-KT88 which I like VERY much. I think George uses them and recommends them as well. I've had a pair of the EH-kt88s running in various amps for years now still test new.

Sovtek 5AR4 as rectifier, noted. I also think that if I can get a real affordable Telefunken rectifier that would be great too.

Bob, for the KT-88, do you know about some people saying they are more suited to the smaller Edcors instead of mine (CXSE-25-8-5K)?

I'll be trying to avoid losing anything in the higher-frequency bands. For great bass, I envision having a subwoofer output as well, so any information on this is helpful too.

For those big Edcors I use EH-KT88 you wont loose anything on the top end and will have enough bass for use without a sub if you main speakers are worthy. George designed this amp to give you full range. Be sure to add in the supplemental cap - you can get that at Partsconnexion as well. For the supplemental cap I like to use 100uF oil filled motor run caps (slightly smaller than soda can size ) - get them on ebay for $15 plus ship - for a big poly cap from Partsconnexion gonna get pricey.

The 440v rating is AC volts - this will be ~660vdc easily so no problem.

A Telefunken 5AR4/GZ34 is going to set you back a hundred or more dollars - save your money and get a Sovtek 5AR4. You can always upgrade tubes later. If you want to get a QUALITY driver 12AT7 - look for the triple mica versions. Again the Telefunken versions are $150 per tube and the GE 5 star versions are $15 or so, gonna be hard to justify the extra $130 for Telefunken. Not a big fan of Teles due to pricing, I have some I'm hording tho. I like the triple mica versions - triple mica is there for extra support to help keep microphonics (noise) to a minimum. Many manufacturers make the triple mica versions. Just don't waste your money on new stock as there are sooo many old stock out there that are much better sounding.

What I usually do is get a cheap set of tubes and build the amp, upgrade the tubes after I have a working amp. there's always a possibility you could smoke an expensive set of tubes with a wiring mistake during build/testing ... hard to do with the SSE but possible.